[SNMP4J] How to Verify the Snmp session is still alive.

[Marco Matchefts]

The Snmp object doesn't have an ::isAlive method to verify that it

is still alive.  What is the best way to verify the snmp session is

still alive?  It looks as though the Default TransportMapping
implementations

spawn a listener thread.  It is possible that they could crash.

It would be nice to know that I could detect problems in the session

and open a new one if necessary.  Any recommendations?  Thanks.